## **Core Concept**
Wormian bones are small, irregular bones found within the sutures of the skull, particularly in the **lambda suture** (located at the back of the head). They are considered a normal variant but can also be associated with certain pathological conditions.

## **Why the Correct Answer is Right**
The correct answer, **lambda suture**, is the location where Wormian bones are most commonly observed. These bones are small, intrasutural bones that can occur due to the intramembranous ossification within the sutures. They are often seen as a benign variant but can be associated with conditions such as **cleidocranial dysplasia**, **osteogenesis imperfecta**, and **Down syndrome**.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because Wormian bones are specifically associated with sutures, not generally with all types of cranial sutures or structures.
- **Option B:** This option is incorrect as there is no commonly recognized association of Wormian bones with a structure referred to as "b" in standard anatomical references.
- **Option D:** This option is incorrect because, while Wormian bones can sometimes be seen in other sutures, they are most characteristically and commonly associated with the lambda suture.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that Wormian bones are often considered a benign finding; however, their presence in a greater number or in specific contexts (such as in certain genetic syndromes) can be clinically significant. For example, multiple Wormian bones are a feature of **cleidocranial dysostosis**.

## **Correct Answer:** . lambda suture